THERMAL-RADIATION FROM ROTATING NEUTRON-STAR - EFFECT OF THE MAGNETIC-FIELD AND SURFACE-TEMPERATURE DISTRIBUTION

In this paper we investigate the anisotropy of the thermal-like radiat ion emitted by the atmosphere of a neutron star with a strong magnetic field. Angular dependences of the fluxes at various photon energies, and spectra at various inclinations of the magnetic axis to the line o f sight are obtained for different distributions of the magnetic field B and effective temperature T-eff over the neutron star surface. We s how that the radiation of the magnetized neutron stars is anisotropic even if T-eff is constant along the star surface. The shape and degree of modulation of the light curves observed from a rotating neutron st ar depend essentially on the surface distributions of T-eff and B. The pulsations at the low-energy and high-energy parts of the spectra may be phase-shifted for not too high effective temperatures. The general properties of the neutron star thermal-like radiation inferred from t he theoretical models are in qualitative agreement with the results of recent ROSAT observations of pulsars of medium age.